Sarcoidosis on Gallium Scan: Panda and Lambda Signs
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Question
A Ga-67 whole-body scan shows increased uptake in the parotid and lacrimal glands along with bilateral symmetric uptake in the hilar and mediastinal lymph nodes. Which interpretation BEST describes the findings on this scan?
- ALambda sign only — bilateral symmetric mediastinal uptake without parotid or lacrimal involvement, consistent with lymphoma rather than granulomatous disease
- BSuperscan pattern — diffuse increased uptake throughout all lymph node regions suggesting widespread systemic infection rather than a focal granulomatous process
- CPanda sign and lambda sign — bilateral parotid and lacrimal gland uptake combined with hilar and mediastinal lymph node uptake, consistent with sarcoidosis
- DNormal Ga-67 biodistribution — parotid gland activity and mild mediastinal uptake are expected findings on any routine whole-body gallium scan
Show the answer and explanation
C. Panda sign and lambda sign — bilateral parotid and lacrimal gland uptake combined with hilar and mediastinal lymph node uptake, consistent with sarcoidosis
This scan shows two classic sarcoidosis patterns: the 'panda sign' (increased Ga-67 uptake in the parotid and lacrimal glands, resembling a panda's face) and the 'lambda sign' (bilateral symmetric hilar and mediastinal lymph node uptake forming a λ shape). When both signs are present together on a Ga-67 scan, this combination is considered highly specific for sarcoidosis. Neither finding alone is pathognomonic, but together they strongly support the diagnosis.
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